Searchers Friday planned to use a heat-seeking drone to help find a firefighter who went missing in the Ventura County mountains a week ago.

Arcadia firefighter Mike Herdman, 36, was hiking last Friday with fellow firefighter/paramedic Taylor Byars at Tar Creek Trail. The two men had set up camp along the Sespe Creek when Herdman’s dog, Duke, ran away.

Byars and Herdman, who was barefoot, ran after the dog.

A short time later, the two men became separated, authorities said. Byars made his way back to the campsite, but Herdman, a seven-year firefighter veteran, and his dog never returned.

Ventura County Search and Rescue crews Thursday concentrated their search in the Sespe Wildnerness area, north of Fillmore, using helicopters and an unmanned drone.

Searchers spotted Herdman’s dog near the creek Wednesday and Thursday, but were unable to find any sign of him.

Investigators said there were no signs of foul play.

Two searchers have been hurt during the effort, with one suffering a leg injury and the other a rattle snake bite.